Preparation of zein solutions directly from gluten



Patented Aug. 8, 1944 PREPARATION OF ZEIN SOLUTIONS DIRECTLY FROM GLUTENRoy E. Coleman, Chicago, 111., assignor to Time Incorporated, acorporation oi New Yorlr No Drawing. Originaiapplication November 30,

1942, Serial No. 467,402. Divided and this application December 18,1942, Serial No. 469,457

Claims.

This invention relates to methods of preparing commercially usablesolutions and coating compositions of prolamines or prolamine-containingproteins directly from glutens, either corn, wheat, barley, etc. It isparticularly directed to such methods which will produce solutions andcoating compositions of the alcoholsoluble portion of corn-gluten, ofcontrolled solution and gelling characteristics;

This application is a division of my copending application, Serial No.467,402, filed November 30, 1942. i I

Heretofore, in the preparation of zein solutions and coatingcompositions, including the substantially non-aqueous zein solutions andcoating compositions of controlled solution and gelling characteristicsas described in my prior Patent No. 2,185,110, granted December 26,1939, g

for example, the zein is initially isolated from corn gluten and thendissolved in suitable solvents to form the desired solutions. To isolatezein from corn gluten as a commercially usable powder'is a laborious andexpensive process, involving steps of precipitation, settling,filtering, washing and drying. The solubility of the zein in zeinsolvents and the solution characteristics such as stability and gellingtendencies are largely dependent upon the care exercised in carrying outthe steps of the process.

In accordance with the present invention I prepare solutions of zein orzein-containing proteins directly from corn gluten under conditionsthat'will readily produce a wide variety of zein products in so far asproperties and solubility characteristics are concerned, and therebyavoid the expense and objections incident to the preliminary isolationof zein in powder form. In carrying out the present invention, corngluten, for example, in granular or powdered form, is treated with asuitable relatively low boiling point zein protein solvent or mixture ofzein protein solvents, without the establishment of special conditionsof hydrogen ion concentration either in the solvent or in the'gluten, toextract the zein from the gluten. The extraction is carried out atelevated temperatures, say from about 120 to about 170 F'., preferablybetween about 140 to about 150 F., for a short period of time generallynot exceeding about three hours. It

is preferred that the extraction time be not longer than about one-halftoabout one hour since within this time and at the temperatures stated,the zein in the gluten isextracted and is not deleteriously afiected.

The extract solution obtained as above describedis now separated fromthe residual gluten by filtration, pressing, centrifugal separation orin any other desirable manner, mixed with a. relatively high boilingpoint zein base solvent to be hereinafter described and distilled orotherwise treated to remove all or some of the relatively low boilingpoint solvent as desired. The

resulting residue is a solution of zein or zeincontaining protein in thezein base solvent alone with all of the relatively low boiling pointsolvent removed, or in the zein base solvent and that portion of therelatively low boiling point solvent which has not been removed. Theresidual gluten, which stillcontains some protein, may be freed fromretained solvent by washing and recovered for further use as a cattlefood or for other purposes.

The resulting zein or zein-containing solu tions in accordance with thepresent invention, over a wide range'of concentrations, are stable onstanding at temperatures of 80 F. and below and do not separate evenwhen cooled to temperatures of 50 to 70 F. and somewhat below. Whencooled even to temperatures as low as 10 above zero or to zero,solutions prepared in accordance with the present invention may separateand become solid; however, on heating again to temperatures of fromabout 45 to 70 F., a re-solution is efl'ected, either without stirringor with slight stirring, and the solutions return to their normal format the re-heating temperatures. In general, these solutions aresubstantially non-gelling and have but a slight tendency to increase inviscosity: that is, to thicken or become heavier in body. In manyinstances 1 they exhibit practically no tendency to thicken or to gelover practical periods of time in the order of about 3 to 6 months andeven up to one year and longer. These solutions remain stable andreasonably constant in their characteristics during the periodsnecessary for transportation and distribution, either in bulk or inpackages,

or for storage for reasonable periods of time,-

proteins extracted in accordance with the methalcohol, is a zeinsolvent.

ods oi' the present invention is largely influenced by the particularsolvent or solvent mixture used to effect extraction as well as by theamounts thereof. For most purposes, about 2% parts by weight of solventto about 1 part by weight of gluten is sufllcientto remove substantiallyall of the extractable zein protein.- More or less solvent may be used,as desired, as is evident from the specific illustrative examplesherein.

In accordance with the present invention the amount of base solventadded to the extract solution should be in a proportion to the amount ofrein or other prolamine in the extract solution corresponding to thedesired concentration of the prolamine in the resulting stable solution.For example, using a corn gluten containing 60% of protein with anestimated extraction of 65%. 39 lbs. or zein are available in 100 lbs.of the gluten. On the basis of producing a final solution in a basesolvent of a solids content of. then 156 lbs. of base solvent will berequired for each 100 lbs. of gluten, providing the estimated amount ofsoluble protein is extracted. It is evident that the protein content orthe extract solution may be determined prior to the admixture of basesolvent with the extract solution, thereby making possible thedetermination of the precise amountoi' base solvent to be added to theextract solution to obtain the desired concentration of zein protein inthe final solution.

The zein protein extracting solvents in ac- .cordance with the presentinvention may be,

suitably, a single solvent or a solvent mixture which is a solvent forsein or other prolamine and which has a' boiling point below about 125C. and, preferably, of about 100 C. and below. Thus, the extractingsolvent may-be one or more of the well-known alcoholic zein solventssuchas anhydrous methanol, or constant boiling point mixtures(azeot'ropes') of aliphatic alcohols such as 95% ethyl alcohol 'and. 91%isopropyl' alcohol.

For convenience herein I term these alcoholic solvents "concentratedalcohol solvents." The extracting solvents may also be one or more ofstated. For convenience herein I term these alcoholic solvents aqueousalcohol mixtures.

, Another class of extracting solvents in accordshoe with the presentinvention comprises mixtures of an azeotropic concentrated alcoholsolvent with a non-solvent and water. Examples of such solvents aremixtures oi',95% ethyl alco-' hol or 91% isopropyl alcohol withdichlorethylene, trichlore'thylene. ethyl acetate, benzene.

cyclohexane, etc., and water. In this class of extracting solvents Ialso include mixtures of alcohol and non-solvents as disclosed in myprior Patent'No. 2,185,123, granted December 26, 1939, and non-aqueousazeotropic mixtures oi anhydrous methyl alcohol with hexane,cyclohexane-benzene, carbon tetrachloride, dichlorethylene,trichlorethylene, acetone; methyl acetate, ethylacetate, methyl ethylketone, etc.. because'one constituent of the mixture, methyl In additionto the roresoing, wherein at least one constituent of an extractingsolvent mixture suitable azeotropic mixtures which are zeirl proteinsolvents wherein the individual constituents of the mixture arenon-solvents for 'zein proteins. Thus, they may be azeotropic mixturesof water on the one hand and dioxan or butyl alcohol on the other.Dioxan forms with water a constant boiling point mixture containing 80%dioxanboiling at 86.9 C.; and butyl alcohol forms with water a constantboiling point mixture containing 63% butyl alcohol boiling at 92 G- Ingeneral, extracting solvents consisting of or' including the aqueousalcohol mixtures are capable of extracting larger .amounts of zeinprotein from gluten than are the extracting solvents consisting of orincluding a concentrated alcohol solvent. It has geen noted that forpractical extraction procedures, using either a concentracted alcoholsolvent alone or an aqueous alcohol mixture alone-approximately 2% partsby weight of solvent to 1 of gluten may be used. At this concentration,with gluten containing approximately 60% total protein, the extractsolutions of the concentrated alcohol solvent contain a maximum zeinprotein content of approximately 10% whereas the extract solutions ofthe aqueous alcohol mixture solvents contain a maximum zein proteincontent of from about 12% to about 15% and even up to 20%. In addition,the aqueous alcohol mixture solvents are capable of extracting asubstantially larger proportion of a desirable type of zein present in.the protein of the gluten than are the concentrated alcohol solvents.

The base solvents are relatively high boiling compounds or mixtures ofcompounds having a boiling point above about C., preferably above aboutC. and having asuitable balance between the hydrocarbon constituents orradicals present in the solvent or solvent mixtures and the polarconstituents or radicals present therein. A certain proportion ofhydroxyl radicals in the base solvents is required to secure and Onehand, having 53% hydroxyl and 47% hydrocarbon radicals, and absoluteethanol on the other hand having 37% hydroxyl and 63% hydrocarbonradicals. The benzyl radical acts as if it were intermediate the methyland ethyl radicals; This range is approximate and may vary somewhatdepending on the solvent or solvent mixture used. The limits of thisrange are indicative of solvent properties and provide a close andadequate guide to enable the operator, by simple experimentation, todetermine the reis a zein solvent, the extracting solvents may be 16quired balance of polar and hydrocarbon radicals in the base solvent ormixture of base solvents in accordance with the present invention.

It may be stated that the base solvents in accordance with the presentinvention may be any one of the solvents or mixture of solventsdescribed in my prior Patent No. 2,185,110 which has the requiredbalance of polar and non-polar radicals, and a boiling point above about125 0., preferably, above about 150 C. as pointed out above. For a morecomplete description of the 'oi' zein or zein-containing proteins in themore kindsof solvents which may be used as base solvents in accordancewith the present invention than is disclosed hereinyreference is made tothe description of these solvents in my prior Patent No. 2,185,110.

Examples of base solvents in accordance with the present invention arethe glycols such as diethylene glycoL propylene glycol; triethyleneglycol and mixtures thereof, including mixtures which contain ethyleneglycol; diacetone alcohol; closed chain cyclic alcohols such as ben zylalcohol, cyclohexanol, furiuryl alcohol, tetrahydrofurfuryl alcohol andmixtures of closed chain alcohols; glycol ethers such as ethylene glycolmono-methyl ether, diethylene glycol monomethyl ether, ethylene glycolmono-ethyl ether, diethylene glycol monoethyl and mixtures of glycolethers; mixtures of two or more of the foregoing enumerated basesolvents; mixtures of one or more of the foregoing base solvents withglycerine, or other solvents or mixtures of solvents, providing themixture has the required polar to non-polar radical balance and therequired relatively high boiling point. It is to be understood that theforegoing specifically mentioned solvents or mixtures of solvents arenot intended to be inclusive of all the base solvents which may be usedin accordance with the present invention since they are merely set forthfor illustrative purposes.

It would appear that the zein base solvents could be used alone toextract prolamine from gluten and thus obtain the desired solutions.Practical considerations, however, preclude their use in this manner.When the base solvents are used alone as the extracting media theyshould be used in proportions to provide at least about 3 to 3% parts byweight of solvent to 1 part by weight of gluten. alone are notparticularly etfective inextracting prolamine from gluten, the resultingsolutions have a low prolamine content, generally not in excess of byweight and usually considerably less. Due to the high boiling points ofthese solvents, concentration of the solutions to 'a higher prolaminecontent is diflicult and impractical.

In general, in the concentration of zein or other prolamine incommercially usable solutions containing about 12 to 30% of protein, theamount of zein base solvent necessary to obtain these concentrations inthe final solutions is in and of itself insuficient to give the properrelation between solvent and gluten for effective extraction results. Iflarge amounts of the relatively high boiling point base solvents areused, suflicient to give the proper relation between solvent and gluten,the extraction results-are not suiliciently effective and, moreover, thecost of treating the extracts to obtain the desired solids concentrationis so prohibitive'as to make this procedure commercially unfeasible aspointed out above.

It is possible, in accordance with prior art teachings, to extract zeinor zein-containing protell i from gluten by the use of anhydrousmethanol or constant boiling point mixtures of the alcoholic solventssuch as- 95% ethyl alcohol and 91% isopropyl alcohol to obtain extractsolutions which can be concentrated to a desired zein content and stillmaintain uniform solvent composition. Such solutions, however, have avery limited use, due largely to the character of the zein extracted bythe solvents and to the solvents themselves. It is evident that extractsolutions Because the base solvents aqueous alcoholic solvents cannot beconcentrated and still maintain a constant solvent composition. Zeinsolutions-of a desired concentration and of a wide applicability can beobtained directly from gluten by having in the final solution as theonly solvent or as the main solvent for-zein. a relatively high boilingpoint solvent having the required balance of polar and nonpolar radicalsas described herein. It is now well established that the viscosity,gelling tendencies,

and practical usability of zein solutions are in no small part dependentupon the character of the solvent in which the zein is dissolved.

Zein or zein-containing extract solutions containing. any one or more ofthe foregoing base solvents, in accordance with the present inventionmay be boiled, distilled or otherwise treated to remove part or all ofthe diluent. It is evident that practically all of the extractingsolvent, including any water carried from the gluten to the extractsolution, may be removed, thereby obtaining solutions of zein orzein-contalning proteins, in the base solvent which, for all practicalpurposes, are substantially anhydrous. Such solutions vary widely incharacter, depending upon the choice of solvents or solvent mixturesused,

as is to be expected, and some of them may undergo changes (apparentinsolubility, for ex' ample), during the solvent and water removal whicheffect the solvent characteristics of the zein and zein-containingproteins in the base solvent utilized. These changes, where they takeplace, are not of a permanent character and it is possible to efl'ect are-solution of the zein or zein-containing proteins in the base solventsby the addition of a small amount of water, say in the order of fromabout 1 to 3% by weight, or an equivalent amount of other highlyhydroxylated compound, such as methyl or ethyl alcohol or a mixture ofsuch compounds.

In the preparation of usable solutions having a wide field ofapplicability, I prefer that the removal of the relatively low boilingpoint solvent and water be controlled so as to leave in the finalsolutions at least about 1 to 3% by weight of water or an equivalentamount of other highly hydroxylated compound-preferably water. Wherethis is not possible, water may be added to the final solution, in theamounts stated. While water is, in general, not an essential constituentof some of the solutions formed in accordancewith thepresent invention,the solutions are generally of an improved character when they containsmall amounts of water. The solutions may contain larger amounts ofwater, say between 5 to 10%,.

or even more.

As already pointed out, the type or character of the zein-containingprotein produced by the extraction is in no small part dependent on thecharacter of the extraction solvents used. This condltionis particularlypronounced when the highly aqueous alcohols or the high water azeotropessuch as dioxan-water or n-butyl alcoholwater mixtures are used asdiluents. Not only do these solvents eflect the'extraction of a largeramount of the zein-containing protein than do the more concentratedalcohols, but they also produce by their extraction a type of zeinprotein which generally produces solutions having a high viscosity andpronounced colloidal consistency. On the other hand the zein proteinproduced with the concentrated alcohols and less aqueous diluents tendsto produce solutions having a lower viscosity and a lessercoiloidal'consistency- .It is thus evident that various types of zeinprotein having substantially different properties can be produced byproper selection and composition of the extracting solvents.

From the foregoing it is manifest that the nature and properties of thefinished solution will be determined by the amount of zein proteinpresent in the solution, the type or character of the zein proteinextracted by the particular extracting solvent used and by the nature ofthe base solvent. It is apparent that with the extracting. solvent andbase solvent combinations possible, a wide variety of solutions for manyuses can be produced by the method of the present invention.

Within the range of the many possible combinations and the method inaccordance with the present invention, solutions may be produced whichrequire further adjustment or modification in order to secure improvedsolution or desired stability and controlled gelling properties. Suchadjustments or modifications can be readily effected by the use ofrosin, fatty acids, compatible amines such as monoethanolamine. trieth-'anolamine, etc., amine soaps of rosin or fatty acids, or bythe variousmethods and materials for producing stable. controlled gelling, zeinsolutions described in my issued Patents Nos. 2,185,122; 2,246,779 and2,298,548. The addition of suitable materials for effecting desiredmodification or adjustment may'be made to the extract solutioncontaining the base solvent before distilling on the extracting solventor to the final solution. The preferable procedure and materials withparticular solutions may. be easily determined by experimentation.

In the following examples I disclose illustrative methods for producingzein or zein-containing solutions directly from gluten in accordancewith the present invention. In the examples end elsewhere throughout thespecification, the term "parts indicates parts by weight.

Example 1.-600 parts of 91% isopropyl alcohol were added to 105 parts rpowdered gluten in a vessel. The mixture was heated to about 180 F. andheld at about that temperature for about hour with stirring to extractthe sein- -containing proteins from the gluten. The mixture was thenforced through a filter to separate the zein-containing extract. To 100parts of the extract 40 parts of propylene glycol were added and themixture was slowly heated to about 250' 1". and held at about thattemperature with stirring until cessation of visible boiling. .Theresih'ol (Synasol"), and 30% of water. 29% parts of diethylene glycolwere added to 50 parts of the extract. The procedure was as in Example 1and the resulting solution was a solution of sein-containing proteinsprincipally in diethylene glycol. Example 4.--29 parts of propyleneglycol were added to 50 parts of the extract of Example 3. The procedurewas as in Example 1 and the resulting solution was a'solution ofrein-containing proteins principally in propylene glycol. Example 5.49%parts of diethylene glycol monoethyl ether were added to 50 parts of theextract .of Example 3.v The procedure was as in was as in Example 1 andthe resulting solution was a solution of zein-containing proteinsprincipally in ethylene glycol monoethyl ether,

Ezample'7-30 parts of powdered glutenwere extracted with parts of asolvent mixture consisting of 63% of n-bu'tyl' alcohol and 37% of water.19.3 parts of benzyl alcohol were added to 44 parts of the extract. Theprocedurewas as in Example 1 and the resulting solution was a solutionof zein-containing proteins principally in benzyl alcohol.

Example 8.-20 parts of powdered gluten were .extracted with 60 parts ofdenatured 95% ethyl alcohol (Synasol). 2'7 parts of cyclohexanol wereadded to 45 parts of the extract. The procedure was as in Example 1except that 2% of water was added to the final solut'on. The resultingsolution was a solution of zein-containing proteins principally incyclo-hexanol. a

' Example ill-20 parts of powdered gluten were extracted with 50 partsof a solvent mixture consisting of 60% of 91% isopropyl alcohol and 40%of water. 17% parts of diethylene glycol were added to parts of theextract. The procedure was as in Example 1 and the resulting solut onwas a solution of zein-containing proteins principal ly in diethyleneglycol.

At the cessation of boiling as referred to in the examples someproportion of the lower boiling constituents of the diluent originallyused iture. Considerable proportions of the diluent or of itsconstituents, including water, may remain without causing gelling of thefinal solu- 1 except that the extractions were carried out at 140 F. andthe proportions varied as hereinafter set. forth. In each instance themixture of extract and relativelyhigh boiling point solvent was heateduntil cessation of visible boiling.

Example 2.-75 parts of powdered gluten were extracted with 125 parts ofa solvent mixture consisting of 70% of denatured 95% ethyl alcohol(sold' under the trade-mark "Bynasol"), and 30% of water. 42% parts ofdiethylene glycol were added to.l00 parts of the extract. The procedurewas as in Example. 1 and the resulting solution was a solution ofzein-containing proteins principally inv diethylene glycol.

Esambls 52-75 parts of powdered gluten were tion in reasonable periodsof time. This is particularly true where the glycols are used. In thisrespect the final solutions show differences from solutions ofcommercial zein containing large amounts of water as in the prior art,apparently by reason of some changes in the character or structure ofthe rein-containing proteins of the corn gluten taking place in theprocess of the pared as described above and the coating com-.

- positions prepared therefrom have the proper= extracted with m partsof a solvent mixture I consisting of 70% of denatured 95% ethyl alco- Ilily 'form tough, flexible, non-tacky. hard and ties, particularly whenheated. of being able to "give up" their solvent or solvents readi y,and when applied to a surface they quickly an readgenerally transparentcoatings even when retaining some solvent. The coatings formed by thesezein-containing solutions and coating compositions are very strong andhave adherent properties. In these solutions and coating compositionsthe film forming properties thereof can be built up to produce films ofgreat toughness, flexibility, hardness and gloss. Under normaltemperature conditions, many of the zein-containing solutions or coatingcompositions will produce non-blushing coatings' on drying, without theaid or supplementary anti-blushing agents as in the prior art.

The coating compositions prepared from the above solutions may be usedfor coating, sizing, or impregnating any material, such as paper,textiles, wood, wood pulp and the like. When coated on paper,Cellophane, glass and the like,

a film is formed which possesses the film charac' teristics set forthabove. Since many of these coating compositions have decided adhesiveproperties, they may be used either per se or in comb'nation with othermaterials for uniting or lamin-sing paper, cloth, wood, glass, felt,Cellophane, metals and metal foils and the like.

The characteristics of the zein-containing coating compositions andhence of the ultimate films formed therefrom can be altered at will andas desired by the inclusion ofmodifi'ers, plasticizers, fillers and thelike. Thus, the coating compositions may be modified by the inclusiontherein of common lacquer solvents or lacquer a,ass,ose

ers, and the like which may be used are, of course, influenced by thepurpose intended, the compatibility of the materials in the solutionsand coating compositions, the specific properties desired in the coatingcompositions and the, films deposted therefrom as well as by the knowncharacteristics oi the modifiers, plasticizers and the like utilized.

.ments and the like.

The fillers which may be used are suitable inert, fibrous or powderedmaterials such as cork, mica, sawdust, chalk, magnesite, clay, bentoniteor equivalent colloidal clays, charcoal dust,'pig- Any suitable color aswell as opacity, where desired, may be imparted to the coatingcompositions, as by a pigment or dye, and the amounts of such coloringagents utilized may be varied rather widely to meet any needs in paints,inks, ink bases and the like.

In the preparation of a printing ink or printing ink base, for example,a solution formed as above described is mixed directlywith the desiredpigments, including fillers and coloring plasticizers and the like suchas, for example,

dioxan; the ketones such as acetone, methyl ethyl ketone, di-isobutylketone and the like; the esters such as methyl acetate, ethyl acetate,ethyl butyrate, butyl butyrate, glycol di-acetate, the esters of theglycol ethers and the like; the alcohol others such as ethylene glycolmonobutyl ether, diethylene glycol monobutyl ether and the like as wellas glycerine derivatives; the

alcohols such as ethanol, denatured alcohol,

butanol, isobutanol, amylalcohol, and higher alcohols such as cetylalcohol, cetyl alcohol, lauryl alcohol, myristyl alcohol and the like;the hydrocarbons such as benzene, toluene, xylene, cyclohexane and thelike; chlorinated compounds such as ethylene dichloride,monochlorobenzene, orthodichlorobenzene, dichloroethyl ether and thelike; iurane derivatives such as furfuryl acetate, furfural and thelike; and plasticizing esters such as dimethyl phthalate, dibutylphthalate, diethyl phthalate, tricresyl, and triphenyl phosphates andthe like- It is obvious from the fore- Boing that other well-knowncommon lacquer solvents, lacquer plasticizers and the like may be usedin lieu of those hereinabove set forth.

The characteristics such as spread and fiow of these, coatingcompositions may also be modified by the addition of a fatty acid suchas, for example, oleic, linseed. hemp seed, lauric and like fatty acidshaving 8 or more carbon atoms in the chain: by the inclusion of fattyacid glycerides,

either raw or treated, such as raw or bodied linseed, China-wood oil orthe like. If desired, compatible natural and synthetic resins such as,for example, rosin, sandarac, copal, phenol-aldehyde, urea-aldehyde,BlYcerin-phthalic anhydrid, vinyl and like resins, or compatiblecellulose derivatives such as, for example, high and low viscositynitrocellulose, celiulose'acetate, ethyl cellulose and like cellulosederivatives may be incorporated in the coating compositions in variousproportions to meet anydesired needs.

The choice and quantity of modifiers, plasticizagent or mixtures thereofby any of th known methods such as by rinding in a stone paint mill,roller mill, ball mill or the like. If desired the pigmentsv may bedispersed in a suitable medium which is compatible with the zeinvehicle, and the dispersed pigments may then be mixed with the zeinvehicle added to form the ink or ink base or the pigments may be roundor dispersed in a mixed vehicle containing the zein solution with suchother vehicles as may be desired. The dispersing medium or other vehiclemay suitably be afatty acid such as linseed fatty acid, scya bean fattyacids, oleic acid, pine fatty acids (tall-oil) and the like, or fattyacid glycerides, resin and oil and oil varnish compositions and the likewhich are compatible with the zein solution used. The proportions ofpigments, coloring agent or agents to the vehicle may vary widely toproduce inks of varying consistencies to meet any desired need. Thus, Ihave produced suitable inks or ink bases wherein the pigment contentvaries from about 2% to about 85% by weight and the vehicle from about15% to about 98%. These inks may vary in consistency from a thick smoothpaste to a thin, free flowing liquid.

The-pigments and coloring agent or agents utilized in printing inksprepared from solutions in accordance with my invention may suitably bea black color such as, for example, carbon black, lamp black, animal orbone black and the like; aprecipitated color such as for example,cadmium yellow, cadmium red, Prussian blue, ultramarine blue and thelike; earth colors such as ochres, siennas, iron oxides and the like;white pigments such as white lead, zinc oxide, titanium oxide, lithoponeand the like; organic colors such as naphtholyellow S, Persian orange,lithol red, cosine, rhodamine, quinoline yellow, indigo, methyl violetand, the like: and combinations of these colorin C ts with fillers suchas blanc flxe, barytes,.asbestine, calcium carbonate, China clay, satinwhite and white pigments such as titanium oxide, lithopone, zincoxideflwhite lead and the like.

It is, of course, obvious that the choice of the particular solution orvehicle combination uti lized in preparing a printing ink is influencedby the propertes desired in the ink and by the compatibility of theingredients constituting the vehicle with the pigments and coloringagent or agents. By a proper'choice of the solvents and of suitablemo'dliying agents, the inks produced may be controlled as toconsistency, drying time, flow, penetration, gloss, tendency towardthickening and action on the printing presses and the like. The choiceofpigments and coloring agent or agents employed is likewise influencedby, the properties desired in ,the inks as well as by the character ofthe vehicle with which it is to be mixed and the compatibility of thepigments and coloring agents with the particular solution or vehicleused. 'The pigment and vehicle combinations should be of such characterthat undue thickening or livering does not take place.

, What has been said hereinabove with specific reference to printinginks obviously applies, in general, to paints, sizes and like coatings.

While my invention has been described in connection with certainspecific examples, it is, of course, obvious that it is" not to beconstrued as limited to these examples or to the details of the methodsset forth therein, since obvious changes in materials, proportions andmethod details will be apparent from the foregoing.

In the claims, the expression zein-containing protein'solvent" refers toany one of the relative- 157 high boiling point solvents having therequired polar to non-polar balance described above or to mixtures ofthese solvents. The expression an elevated temperature in the order ofabout 120 F. to about 170 F." is not to-be construed as apre'cisecritical range, but, rather, as a range of temperaturesindicative of the elevated temperature at which the extractions may becarried out. Temperatures below about 120 F. and temperatures aboveabout 170 F. may, obviously, be used.

Thus, for example, in the foregoing illustrative Example 18, anextraction temperature in the order of about 180 F. is used.

I claim: 1. The method of preparing directly from I gluten a solution ofzein-containing proteins in a solvent or mixture of solvents comprisingas an essential solvent constituent for the zein-containing proteins, asolvent having a boiling point above about 125 C. and having aproportion of polar to non-polar radicals which lies within a rangeextending between the limits of the proportion of polar to non-polarradicals of methanol and the proportion of polar to non-polar radicalsof ethanol, which comprises contacting gluten with a zein proteinsolvent having a boil- 1 8 point below about 125 C. at an elevatedtemperature inthe order of about 120 F. to about 170 F. to extract sem-containing proteins from the gluten, separating the extract solutionfrom the residual gluten, mixing the aforesaid solvent having a boilingpoint above about 125 C. with said extract solution and removing atleast part of said relatively low boiling point'solvent fromthe-solution.

2. The method of preparing directly from gluten a solution ofzein-containing proteins in a solvent or mixture of solvents comprising'as an essential solvent constituent for the zein-contaming proteins, asolvent having a boiling point above about 150' C.-and having aproportion of polar to non-polar radicals which lies within a rangeextending between the limits of the proporgluten, mixing azein-containing protein sol-- gluten a solution of zein-containingproteins 'in a solvent or mixture of solvents comprising as an essentialsolvent constituentfor the zein-containing proteins, a solvent having aboiling point above about 150 C. and having a proportion of polar tonon-polar radicals which lies within a range extending between thelimits of the proportion of polar to non-polar radicals of methanol andthe proportion of pollar to non-polar radicals of ethanol, whichcomprises contacting gluten with a zein protein solvent having a boilingpoint below about C. at an elevated temperature in the order of about120 F. to about 170 F. to extract ain-containing proteins from thegluten, separating the extract solution from the residual gluten, mixinga zein-containing protein solvent comprising the aforesaid solventhaving a boiling point above about C. with said extract solution andremoving at least part of said relatively low boiling point solvent fromthe solution.

4. The method of preparing directly from gluten a solution ofzein-containing proteins in a solvent or mixture of solvents comprisingas an essential solvent constituent for the zein-containing proteins, asolvent having a boiling point above about 150: C. and having aproportion of polar to non-polar radicals which lies within a rangeextending between the limits of the proportion separating the extractsolution from the residual gluten, mixing a zein-containing proteinsolvent comprising the aforesaid solvent having a boiling point aboveabout 150 C. with said extract solution andremoving at least part ofsaid relatively low boiling point solvent from the solution.

5. The method of preparing directly from gluten a solution ofgain-containing proteins in asolvent or mixture of solvents comprising aglycol as an essential solvent constituent for the zein-containingproteins, which comprises contacting gluten with a zein protein solventhaving a boiling point below about 125 C. at an elevated temperature inthe order of about 120' I".

' to about F. to extract zein-containing protion of polar to non-polarradicals of methanol and the proportion of polar to non-polar radicalsof ethanol, whi :h comprises contacting gluten with a aein proteinsolvent having a boiling point below.about 125 C. at an elevatedtemperature m the order r about 120 F. to about 1'10 s. to

extract em-containing proteins from the gluten,

separating the extract solution. from the residual teins from thegluten, separating the extract solution from the residual gluten, mixinga zein-containing protein solvent comprising a glycol with said extractsolution and removing at least part of said relatively low boiling pointsolvent from the solution.

6.- The method of preparing directly from gluten a solution ofzein-containing proteins in a solvent or mixture of solvents comprisinga glycol as an essential solvent constituent for the em-containingproteins, which comprises contacting gluten with a zein protein solventhaving a boiling point below about 125 C. at an elevatedtemperature in.the order of about 120' 1". to about 170 ,1". to extractzein-containing proteins from the gluten; said zein protein solventassaose tract solution and removing at least part oi said relatively lowboiling point solvent from the solutionQ 7. The method of preparingdirectly from .gluten a solution 0! zein-containlng proteins in asolvent or mixture of solvents comprising a glycol as an essentialsolvent constituent for the min-containing proteins, which comprisescontacting gluten with a zein protein solvent having a boiling pointbelow about 125 C. at an elevated temperature in the order of about 1201". to about 170 F. to extract zein-containing proteins from the gluten,said zein protein solvent being an azeotropic mixture of an alcoholhaving tein solvent comprising propylene glycol with said extractsolution and removing at least part of said relatively low boiling pointsolvent from.

the solution.

9. The method of preparing directly from gluten a solution oi!zein-containing proteins in a solvent or mixture oi! solvents comprisingcyclohexanol as an essential solvent constituent for the zein-containingproteins, which comprises contacting gluten with a relatively lowboiling point zein protein solvent comprising 95% ethyl alcohol at anelevated temperature in the order 1 0! about 120 1". to about 170" F. toextract min- I containing proteins from the gluten, separating tromtwoto tour carbon atoms in the molecule and water, separating the extractsolution from the residual gluten, mixing a coin-containing proteinsolvent comprising a glycol with said extract solution and removing atleast part of said relatively low boiling point solvent from thesolution.

8. The method oi preparing directly from gluten a solution orzein-containing proteins in a solvent or mixture of solvents comprisingpropylene glycol as an essential solvent constituent tor thezein-containing proteins, which comprises contacting gluten with arelatively low boiling point zein protein solvent comprising 91%isopropyl alcohol at an elevated temperature in the order or about 1201''. to about 170 F. to extract zein-containing proteins from thegluton. separating the extract solution from the residual gluten, mixinga rein-containing prothe extract solution from the residual gluten,mixing a min-containing protein solvent comprising cyclohexanol withsaid extract'solution and removing at least part or said relatively lowboiling point solvent from the solution.

10. The method of preparing directly from gluten a solution oi.zein-containing proteins in a solvent or mixture of solvents comprisingdiethylene glycol as an essential solvent constituent for therein-containing proteins, which comprises'contacting gluten with arelatively low boiling point zein protein solvent comprising 95% ethylalcohol and water at an elevated temperature in the order oi about 120F. to about 170 F. to extract min-containing proteins from the gluten,separating the extract solution from the residual gluten, mixing amin-containing pro= tein solvent comprising diethylene glycol withsaidextract solution and removing at least part .oi'said relatively lowboiling point solvent from the solution.

ROY E. COLEMAN.

